I would say that wear on one of these front end components may be typical of almost 60,000 miles of use, probably hard use would explain it better, like lots of pothole city driving, or very aggresive driving. It is unusual that the mechanic is finding unacceptable wear on so many components. The link between the steering gear box and lower steering column shaft I would consider very unusual.
If at all possible, see if you can change the mass air flow sensor yourself, it is a very easy job. BUT the check engine light will need to be reset, ie "turned off", it won't go out by itself.
I checked on the codes, it is as MB DOC explained, the self-adaptation is at the limits, and the mass airflow sensor is the usual problem, happens alot with all manufacturers, not just MB.
The PO170 is for the right bank of cylinders, the PO173 is for the left bank. Sorry about the confusion with mentioning misfire codes, I believe MB DOC is correct with mentioning PO300 codes are misfire codes, then there are codes such as PO301 indicating #1 cylinder and so on.
I would also follow up on the advice concerning trying to get MB to cover the cost under warranty for the check engine light, it should be covered whether you are the original owner or not.....